I. Field of the Invention
The present invention relates to conveyor systems having disengageable load carriers and more particularly to a device for stopping and disengaging a carrier in such a system.
II. Description of the Prior Art
Conveyor systems, such as "power and free conveyors" have load carriers which may be selectively released from a propelling mechanism. A power and free conveyor includes a "power line" and a number of load carriers suspended on a carrier track. The "power line" includes a propelling mechanism for the carriers and is supported for continuous movement on a power track.
The "power line" is mounted adjacent to the carrier track. Load carriers are suspended from the carrier track on trolleys. Each trolley has a driving mechanism which engages a pusher of the propelling mechanism. The driving mechanism includes a retractable driving dog and a hold-back dog. The pusher is held between the dogs to propel the carrier.
Wayside stopping stations are provided to selectively disengage the pusher from the carrier and hold the carrier in position while an operation, such as loading or unloading, is performed. The carriers are disengaged from the pusher by extending a stop plate into the path of travel of the driving mechanism to retract or depress the driving dog. The stop plate, thus, releases the pusher and then abuts against a stop engagement surface to hold the carrier.
Previously known stopping devices utilized mechanical assemblies or pneumatic systems to extend and retract the stop plate. These assemblies operate at a relatively slow speed in extending and retracting the stop plate. In environments having dust, dirt, or other contaminants, it is necessary to carefully protect the mechanical assembly from clogging and jamming. Pneumatic systems are noisy and require extensive and expensive air supply systems and large compressors.
Accordingly, it would be advantageous to provide a simple and inexpensive stop assembly which is not sensitive to environmental conditions and which is rapidly extended and retracted.